Table 1 Reaction optimization.
| ||
|---|---|---|
Entry | Change from above conditions | Yield (%) |
1 | none | 87(81) |
2 | THF instead of 1,2-DME | 84(78) |
3 | Ni(NO3)2.6H2O as the catalyst | 69 |
4 | NiCl2.6H2O as the catalyst | 67 |
5 | NiCl2 with H2O (3.0 equiv) | 54 |
6 | no Ni catalyst | 0 |
7 | no Zn | 0 |
8 | no ZnCl2 | 0 |
9 | Mn instead of Zn | 49 |
10 | MgCl2 instead of ZnCl2 | 18 |
11 | 1.0 equiv of 2 | 41 |
12 | open atmosphere | 66 |
13 | 12 h | 68 |
14 | 10 mol% of Ni catalyst | 68 |
15 | 4-methoxybenzoyl chloride | 0 |
16 | 4-methoxybenzaldehyde | 0 |
17 | 2-mercaptopyridine, 20 mol% | 65 |
18 | 2,2′-dipyridyl disulfide, 20 mol% | (48) |
